(a) Field of the Invention
The present invention relates to a light source for a device displaying images.
(b) Description of the Related Art
Devices for displaying images, such as television receivers, computer monitors or the like, are classified into self-luminescence display devices capable of self-emitting and light receiving display devices necessitating a separate light source. Light emitting diode (LED), electroluminescence (EL), vacuum fluorescent display (VFD), field emission display (FED), and plasma display panel (PDP) devices, etc. are included in the self-luminescence display device category, while liquid crystal display (LCD) devices, etc. are included in the light receiving display device category.
Generally, an LCD device includes a pair of panels individually having electrodes on their inner surfaces, and a dielectric anisotropy liquid crystal layer interposed between the panels. In the LCD device, a variation of the voltage difference between the field generating electrodes, i.e., a variation in the strength of an electric field generated by the electrodes, changes the transmittance of light passing through the liquid crystal layer, and thus desired images are obtained by controlling the voltage difference between the electrodes.
In the LCD device, the light may be natural light or artificial light emitted from a light source separately employed in the LCD device.
A backlight unit is a representative device for providing the artificial light to the LCD device. Light emitting diodes (LEDs) or fluorescent lamps such as cold cathode fluorescent lamps (CCFLs), external electrode fluorescent lamps (EEFLs), etc. may be utilized as a light source of the backlight unit.
The LED has eco-friendly characteristics since it dose not use mercury (Hg) and its working lifetime is longer than the lifetimes of most other light sources due to its stable characteristics. For at least these reasons, the LED may be used as a next-generation light source.
However, the light emitted from the LED tends to be condensed to a substantially narrow area. For applying such an LED to a surface light source, therefore, a technique that is capable of distributing the light from the LED to a wider region is required in this field. For this reason, a space only used for uniformly distributing such a light may be further provided in the device. In a direct-type backlight, such a space may increase the thickness of the backlight, while forming a dead space at both sides of the LCD panel in an edge-type backlight. As a result, it may be incongruent to apply such a space to designs for fabricating compact, slim, and light LCD devices.